 /*
  * $Header: /cvshome/build/org.osgi.service.event/src/org/osgi/service/event/TopicPermission.java,v 1.11 2006/06/16 16:31:48 hargrave Exp $
  *
  * Copyright (c) OSGi Alliance (2005, 2006). All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package org.osgi.service.event;

 import java.io.IOException ;
 import java.security.Permission ;
 import java.security.PermissionCollection ;
 import java.util.Enumeration ;
 import java.util.Hashtable ;

 /**
  * A bundle's authority to publish or subscribe to event on a topic.
  *
  * <p>
  * A topic is a slash-separated string that defines a topic.
  * <p>
  * For example:
  *
  * <pre>
  * org/osgi/service/foo/FooEvent/ACTION
  * </pre>
  *
  * <p>
  * <code>TopicPermission</code> has two actions: <code>publish</code> and
  * <code>subscribe</code>.
  *
  * @version $Revision: 1.11 $
  */
 public final class TopicPermission extends Permission {
     static final long serialVersionUID = -5855563886961618300L;
     /**
      * The action string <code>publish</code>.
      */
     public final static String PUBLISH = "publish"; //$NON-NLS-1$
 /**
      * The action string <code>subscribe</code>.
      */
     public final static String SUBSCRIBE = "subscribe"; //$NON-NLS-1$
 private final static int ACTION_PUBLISH = 0x00000001;
     private final static int ACTION_SUBSCRIBE = 0x00000002;
     private final static int ACTION_ALL = ACTION_PUBLISH
                                                             | ACTION_SUBSCRIBE;
     private final static int ACTION_NONE = 0;
     /**
      * The actions mask.
      */
     private transient int action_mask = ACTION_NONE;

     /**
      * prefix if the name is wildcarded.
      */
     private transient String prefix;

     /**
      * The actions in canonical form.
      *
      * @serial
      */
     private String actions = null;

     /**
      * Defines the authority to publich and/or subscribe to a topic within the
      * EventAdmin service.
      * <p>
      * The name is specified as a slash-separated string. Wildcards may be used.
      * For example:
      *
      * <pre>
      * org/osgi/service/fooFooEvent/ACTION
      * com/isv/*
      * *
      * </pre>
      *
      * <p>
      * A bundle that needs to publish events on a topic must have the
      * appropriate <code>TopicPermission</code> for that topic; similarly, a
      * bundle that needs to subscribe to events on a topic must have the
      * appropriate <code>TopicPermssion</code> for that topic.
      * <p>
      *
      * @param name Topic name.
      * @param actions <code>publish</code>,<code>subscribe</code>
      * (canonical order).
      */
     public TopicPermission(String name, String actions) {
         this(name, getMask(actions));
     }

     /**
      * Package private constructor used by TopicPermissionCollection.
      *
      * @param name class name
      * @param mask action mask
      */
     TopicPermission(String name, int mask) {
         super(name);
         init(name, mask);
     }

     /**
      * Called by constructors and when deserialized.
      *
      * @param name topic name
      * @param mask action mask
      */
     private void init(String name, int mask) {
         if ((name == null) || name.length() == 0) {
             throw new IllegalArgumentException ("invalid name"); //$NON-NLS-1$
 }

         if (name.equals("*")) {
             prefix = "";
         }
         else
             if (name.endsWith("/*")) {
                 prefix = name.substring(0, name.length() - 1);
             }
             else {
                 prefix = null;
             }

         if ((mask == ACTION_NONE) || ((mask & ACTION_ALL) != mask)) {
             throw new IllegalArgumentException ("invalid action string"); //$NON-NLS-1$
 }
         action_mask = mask;
     }

     /**
      * Parse action string into action mask.
      *
      * @param actions Action string.
      * @return action mask.
      */
     private static int getMask(String actions) {
         boolean seencomma = false;
         int mask = ACTION_NONE;
         if (actions == null) {
             return mask;
         }
         char[] a = actions.toCharArray();
         int i = a.length - 1;
         if (i < 0)
             return mask;
         while (i != -1) {
             char c;
             // skip whitespace
 while ((i != -1)
                     && ((c = a[i]) == ' ' || c == '\r' || c == '\n'
                             || c == '\f' || c == '\t'))
                 i--;
             // check for the known strings
 int matchlen;
             if (i >= 8 && (a[i - 8] == 's' || a[i - 8] == 'S')
                     && (a[i - 7] == 'u' || a[i - 7] == 'U')
                     && (a[i - 6] == 'b' || a[i - 6] == 'B')
                     && (a[i - 5] == 's' || a[i - 5] == 'S')
                     && (a[i - 4] == 'c' || a[i - 4] == 'C')
                     && (a[i - 3] == 'r' || a[i - 3] == 'R')
                     && (a[i - 2] == 'i' || a[i - 2] == 'I')
                     && (a[i - 1] == 'b' || a[i - 1] == 'B')
                     && (a[i] == 'e' || a[i] == 'E')) {
                 matchlen = 9;
                 mask |= ACTION_SUBSCRIBE;
             }
             else
                 if (i >= 6 && (a[i - 6] == 'p' || a[i - 6] == 'P')
                         && (a[i - 5] == 'u' || a[i - 5] == 'U')
                         && (a[i - 4] == 'b' || a[i - 4] == 'B')
                         && (a[i - 3] == 'l' || a[i - 3] == 'L')
                         && (a[i - 2] == 'i' || a[i - 2] == 'I')
                         && (a[i - 1] == 's' || a[i - 1] == 'S')
                         && (a[i] == 'h' || a[i] == 'H')) {
                     matchlen = 7;
                     mask |= ACTION_PUBLISH;
                 }
                 else {
                     // parse error
 throw new IllegalArgumentException ("invalid permission: " //$NON-NLS-1$
 + actions);
                 }
             // make sure we didn't just match the tail of a word
 // like "ackbarfpublish". Also, skip to the comma.
 seencomma = false;
             while (i >= matchlen && !seencomma) {
                 switch (a[i - matchlen]) {
                     case ',' :
                         seencomma = true;
                     /* FALLTHROUGH */
                     case ' ' :
                     case '\r' :
                     case '\n' :
                     case '\f' :
                     case '\t' :
                         break;
                     default :
                         throw new IllegalArgumentException (
                                 "invalid permission: " + actions); //$NON-NLS-1$
 }
                 i--;
             }
             // point i at the location of the comma minus one (or -1).
 i -= matchlen;
         }
         if (seencomma) {
             throw new IllegalArgumentException ("invalid permission: " + actions); //$NON-NLS-1$
 }
         return mask;
     }

     /**
      * Determines if the specified permission is implied by this object.
      *
      * <p>
      * This method checks that the topic name of the target is implied by the
      * topic name of this object. The list of <code>TopicPermission</code>
      * actions must either match or allow for the list of the target object to
      * imply the target <code>TopicPermission</code> action.
      *
      * <pre>
      * x/y/*,&quot;publish&quot; -&gt; x/y/z,&quot;publish&quot; is true
      * *,&quot;subscribe&quot; -&gt; x/y,&quot;subscribe&quot; is true
      * *,&quot;publish&quot; -&gt; x/y,&quot;subscribe&quot; is false
      * x/y,&quot;publish&quot; -&gt; x/y/z,&quot;publish&quot; is false
      * </pre>
      *
      * @param p The target permission to interrogate.
      * @return <code>true</code> if the specified <code>TopicPermission</code>
      * action is implied by this object; <code>false</code> otherwise.
      */
     public boolean implies(Permission p) {
         if (p instanceof TopicPermission) {
             TopicPermission target = (TopicPermission) p;
             if ((action_mask & target.action_mask) == target.action_mask) {
                 if (prefix != null) {
                     return target.getName().startsWith(prefix);
                 }

                 return target.getName().equals(getName());
             }
         }
         return false;
     }

     /**
      * Returns the canonical string representation of the
      * <code>TopicPermission</code> actions.
      *
      * <p>
      * Always returns present <code>TopicPermission</code> actions in the
      * following order: <code>publish</code>,<code>subscribe</code>.
      *
      * @return Canonical string representation of the
      * <code>TopicPermission</code> actions.
      */
     public String getActions() {
         if (actions == null) {
             StringBuffer sb = new StringBuffer ();
             boolean comma = false;
             if ((action_mask & ACTION_PUBLISH) == ACTION_PUBLISH) {
                 sb.append(PUBLISH);
                 comma = true;
             }
             if ((action_mask & ACTION_SUBSCRIBE) == ACTION_SUBSCRIBE) {
                 if (comma)
                     sb.append(',');
                 sb.append(SUBSCRIBE);
             }
             actions = sb.toString();
         }
         return actions;
     }

     /**
      * Returns a new <code>PermissionCollection</code> object suitable for
      * storing <code>TopicPermission</code> objects.
      *
      * @return A new <code>PermissionCollection</code> object.
      */
     public PermissionCollection newPermissionCollection() {
         return new TopicPermissionCollection();
     }

     /**
      * Determines the equality of two <code>TopicPermission</code> objects.
      *
      * This method checks that specified <code>TopicPermission</code> has the same topic name and
      * actions as this
      * <code>TopicPermission</code> object.
      *
      * @param obj The object to test for equality with this
      * <code>TopicPermission</code> object.
      * @return <code>true</code> if <code>obj</code> is a
      * <code>TopicPermission</code>, and has the same topic name and
      * actions as this <code>TopicPermission</code> object;
      * <code>false</code> otherwise.
      */
     public boolean equals(Object obj) {
         if (obj == this) {
             return true;
         }
         if (!(obj instanceof TopicPermission)) {
             return false;
         }
         TopicPermission p = (TopicPermission) obj;
         return (action_mask == p.action_mask) && getName().equals(p.getName());
     }

     /**
      * Returns the hash code value for this object.
      *
      * @return A hash code value for this object.
      */
     public int hashCode() {
         return getName().hashCode() ^ getActions().hashCode();
     }

     /**
      * Returns the current action mask.
      * <p>
      * Used by the TopicPermissionCollection class.
      *
      * @return Current action mask.
      */
     int getMask() {
         return action_mask;
     }

     /**
      * WriteObject is called to save the state of this permission object to a
      * stream. The actions are serialized, and the superclass takes care of the
      * name.
      */
     private synchronized void writeObject(java.io.ObjectOutputStream s)
             throws IOException {
         // Write out the actions. The superclass takes care of the name
 // call getActions to make sure actions field is initialized
 if (actions == null)
             getActions();
         s.defaultWriteObject();
     }

     /**
      * readObject is called to restore the state of this permission from a
      * stream.
      */
     private synchronized void readObject(java.io.ObjectInputStream s)
             throws IOException , ClassNotFoundException {
         // Read in the action, then initialize the rest
 s.defaultReadObject();
         init(getName(), getMask(actions));
     }
 }

 /**
  * Stores a set of <code>TopicPermission</code> permissions.
  *
  * @see java.security.Permission
  * @see java.security.Permissions
  * @see java.security.PermissionCollection
  */
 final class TopicPermissionCollection extends PermissionCollection {
     static final long serialVersionUID = -614647783533924048L;
     /**
      * Table of permissions.
      *
      * @serial
      */
     private Hashtable permissions;
     /**
      * Boolean saying if "*" is in the collection.
      *
      * @serial
      */
     private boolean all_allowed;

     /**
      * Create an empty TopicPermissions object.
      *
      */
     public TopicPermissionCollection() {
         permissions = new Hashtable ();
         all_allowed = false;
     }

     /**
      * Adds a permission to the <code>TopicPermission</code> objects. The key
      * for the hash is the name.
      *
      * @param permission The <code>TopicPermission</code> object to add.
      *
      * @throws IllegalArgumentException If the permission is not a
      * <code>TopicPermission</code> instance.
      *
      * @throws SecurityException If this
      * <code>TopicPermissionCollection</code> object has been
      * marked read-only.
      */
     public void add(Permission permission) {
         if (!(permission instanceof TopicPermission))
             throw new IllegalArgumentException ("invalid permission: " //$NON-NLS-1$
 + permission);
         if (isReadOnly())
             throw new SecurityException ("attempt to add a Permission to a " //$NON-NLS-1$
 + "readonly PermissionCollection"); //$NON-NLS-1$
 TopicPermission pp = (TopicPermission) permission;
         String name = pp.getName();
         TopicPermission existing = (TopicPermission) permissions.get(name);
         if (existing != null) {
             int oldMask = existing.getMask();
             int newMask = pp.getMask();
             if (oldMask != newMask) {
                 permissions.put(name, new TopicPermission(name, oldMask
                         | newMask));
             }
         }
         else {
             permissions.put(name, permission);
         }
         if (!all_allowed) {
             if (name.equals("*")) //$NON-NLS-1$
 all_allowed = true;
         }
     }

     /**
      * Determines if the specified permissions implies the permissions expressed
      * in <code>permission</code>.
      *
      * @param permission The Permission object to compare with this
      * <code>TopicPermission</code> object.
      *
      * @return <code>true</code> if <code>permission</code> is a proper
      * subset of a permission in the set; <code>false</code>
      * otherwise.
      */
     public boolean implies(Permission permission) {
         if (!(permission instanceof TopicPermission))
             return false;
         TopicPermission pp = (TopicPermission) permission;
         TopicPermission x;
         int desired = pp.getMask();
         int effective = 0;
         // short circuit if the "*" Permission was added
 if (all_allowed) {
             x = (TopicPermission) permissions.get("*"); //$NON-NLS-1$
 if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return true;
             }
         }
         // strategy:
 // Check for full match first. Then work our way up the
 // name looking for matches on a/b/*
 String name = pp.getName();
         x = (TopicPermission) permissions.get(name);
         if (x != null) {
             // we have a direct hit!
 effective |= x.getMask();
             if ((effective & desired) == desired)
                 return true;
         }
         // work our way up the tree...
 int last, offset;
         offset = name.length() - 1;
         while ((last = name.lastIndexOf("/", offset)) != -1) { //$NON-NLS-1$
 name = name.substring(0, last + 1) + "*"; //$NON-NLS-1$
 x = (TopicPermission) permissions.get(name);
             if (x != null) {
                 effective |= x.getMask();
                 if ((effective & desired) == desired)
                     return true;
             }
             offset = last - 1;
         }
         // we don't have to check for "*" as it was already checked
 // at the top (all_allowed), so we just return false
 return false;
     }

     /**
      * Returns an enumeration of all <code>TopicPermission</code> objects in
      * the container.
      *
      * @return Enumeration of all <code>TopicPermission</code> objects.
      */
     public Enumeration elements() {
         return permissions.elements();
     }
 }

